<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*
            外边距可以重叠
        */
        .box1{
            width: 100px;
            height: 100px;
            background-color: yellowgreen;
            border: #111111 solid 5px;
            margin: 10px;
        }
    </style>
</head>
<body>
<div class="box1">
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</div>
<div class="box1">

</div>
</body>
</html>